Merge pull request #87 from oreillymedia/htmlbook-xsl

Turn off generate.root.chunk by default in chunk.xsl and ensure <iframe> tags are not self-closing
Handling to ensure <script> tags are not self-closing (i.e., no <script/>), as that can cause problems for browsers.
Merge pull request #88 from oreillymedia/script_tag

Handling to ensure <script> tags are not self-closing (i.e., no <script/...
Merge branch 'master' of github.com:oreillymedia/HTMLBook into htmlbook-xsl